The Impact of Recent Morphological and Molecular Studies On Species Boundaries and Interrelationships of Wild and Cultivated Potatoes.

In 1990, the latest comprehensive taxonomic monograph of Solanum section Petota Dumort. recognized 232 species partitioned into 21 series. Recent morphological and molecular studies have drastically altered knowledge of their species boundaries and interrelationships. The series contains diploids (2n = 2x = 24), tetraploids (2n = 4x= 48), and hexaploids (and rare triploids and pentaploids). Problems of species boundaries and interrelationships of sect. Petota have been investigated with morphological phenetics in replicated field trials in the US and Peru, field studies in natural habitats, AFLPs, plastid DNA restriction site data and plastid deletion data, DNA sequences of nuclear orthologs waxy, nitrate reductase, and conserved orthologous set (COSII) markers, and herbarium specimen data, including an examination of nearly all type specimens. Three species Hawkes placed in sect. Petota are now removed to sect. Etuberosum (Buk. & Kameraz) Child (S. etuberosum Lindl., S. fernandezianum Phil, S. palustre Poepp.), two species removed to sect. Lycopersicoides (A. Child) Peralta (Solanum lycopersicoides Dunal, Solanum sitiens I. M. Johnston), and two species to section Juglandifolia (Rydberg) A. Child (Solanum juglandifolium Dunal, Solanum ochranthum Dunal). Within sect. Petota, most series are unsupported, replaced by a three clade classification, with some of the polyploids supported as allopolyploids with parents among these clades. The final taxonomic treatment, in preparation in on-line form (http://www.nhm.ac.uk/research-curation/research/projects/solanaceaesource/), as printed monographs, is recognizing only about half (110) of the 232 species of Hawkes. These comprehensive treatments are encompassing all components of traditional monographs, to include keys, synonyms, typifications, descriptions, images of representative types, distribution maps, line drawings of all recognized species, and over 15,500 locality records of herbarium specimens.